1. Field of the Invention
The present invention relates to a servo case used for radio-controlled models such as model airplanes.
2. The Prior Art
There is a general tendency these days towards the use of smaller models and/or for models that use thinner airfoil sections. Accordingly, there is a need for smaller, thinner and lighter components such as the receiver, receiver battery and servos. A servo normally consists of an electric motor, a reduction gear set that is adapted to a potentiometer, an amplifier, metal shafts and an injection molded housing with case screws.
In a servo having a weight of 10 grams, 40% of its weight comes from the case and the case screws, because the average thickness of the injection molded case normally ranges between 1.0 and 1.5 mm. Reducing the thickness of the case greatly increases the costs of manufacture, due to the increased cost of the injection mold. The thickness of the material not only affects the total weight of the case, but also affects the minimum thickness of the servo case itself. In a servo using components of 10 mm thickness, one must add 1.0 mm thickness on both sides of the components to account for the case, thus leading to a minimum case width of 12 mm.
In extreme models having servos, it has become common to eliminate parts or all of the servo case. However, this is very difficult and dangerous, as the open construction does not allow for a proper fixation of the gear shafts and may cause problems if dirt goes between the gears and blocks them from operating. In addition, wires may become dislodged from the motor, amplifier or potentiometer. These disadvantages make it clear that a servo case is necessary for the safe and efficient operation of the servo.